MacArthur fellow and John Burroughs Award–winner Safina (Song for the Blue Ocean ) presents an impassioned account of the plight of ocean-dwelling turtles, especially the largest, the leatherback, "the closest thing we have to a living dinosaur." Leatherbacks, which can weigh over a ton, range the oceans to nesting sites on beaches along the Atlantic and Pacific seaboards. Safina travels to many of these sites, bringing the reader into the turtles' world as he describes how the females leave the ocean, cross sandy beaches, dig huge pits using their flippers as spades, lay their eggs and then creep back into the sea. He shows how precarious this world is; nature's dangers are always present, but it's human activities that threaten the turtles with extinction: poaching, longline fishing nets in which the turtles can drown and depletion of the turtles' food supply due to overfishing and global warming. There are remedies, such as intensive nest-saving programs, but these take time to implement, and time is running out for the turtles. Safina's eloquent book is a battle cry in the struggle for the survival of one of the world's most beautiful and endangered creatures. Maps. (June 27)